EXALTONE.RTM. and muscone, two macrocyclic ketones, are very appreciated in the art of perfumery for their elegant and tenacious musky odour. Both compounds have been known for several decades and since their discovery a variety of syntheses have been proposed and described in the scientific literature [see e.g.: J. Chem. Soc. 1964, 4154; Tetrahedron 20, 2601 (1964); Helv. Chim. Acta 50, 705 (1967) and Helv. Chim. Acta 50, 708 (1967)]. So far, however, most of the published methods could not be successfully applied to their industrial scale preparation, especially in view of their complexity or in view of the low yields achieved in the critical reaction steps.
One of the prior known syntheses [Helv. Chim. Acta 50, 705 (1967)] makes use of the compound of formula ##STR5## (R=H, in formula I) as intermediate in the synthesis of EXALTONE.RTM. (cyclopentadecanone), and of the corresponding methyl derivative of formula ##STR6## (R=methyl, in formula I) in the synthesis of muscone. Both intermediate compounds can be obtained from cyclododecanone by a condensation reaction and a subsequent cyclization, hydrogenation and dehydration. Due to the rather poor overall yields achieved, such synthetic routes have not been developed industrially.
The advantage of the invention consists in providing a new and original synthetic process for preparing the above mentioned intermediate compounds of formula (I), thus making the preparation of the desired macrocycles more convenient and industrially feasible.